Upload
others
View
2
Download
0
Embed Size (px)
Citation preview
Decadal climate predictions for climate services
Freja Vamborg
Max Planck Institute for MeteorologyHamburg, Germany
A framework for decadal climate predictionMiKlip project
Making skillful (and useful) predictions
„Roadmap“ for making decadal climate predictions part of a climate services portfolio
Overview
A framework for decadal climate predictionMiKlip project
Making skillful (and useful) predictions
„Roadmap“ for making decadal climate predictions part of a climate services portfolio
Overview
Decadal climate predictions Climate projections
• An estimate of the actual future evolution of climate
• Predicts anthropogenic change and climate variability
• Initial state based on observations of slow climate components (ocean, others)
• Hindcasts (retrospective predictions) allow to assess skill
• One potential future evolution of climate
• Contingent on emissions scenarios
• Initial state not considered essential
What are decadal climate predictions and how do they differ from climate projections?
Thanks to J. Marotzke, MPI Meteorology
What are decadal climate predictions and how do they differ from climate projections?
Daily Monthly Seasonal Decadal Multi-decadal to centennial
Initial value problem:
Forced boundary condition
Picture: E . Winqvist
Decadal climate predictions - a candidate for climate services?
YES•time-horizon appropriate for decision making •indication of predictability for certain quantities
– Atlantic hurricanes (Smith et al. 2010)– Arctic sea ice, heatwaves, impacts?
Decadal climate predictions - a candidate for climate services?
YES•time-horizon appropriate for decision making •indication of predictability for certain quantities
RECOMMENDATION •develop a system for decadal climate predictions (World Summit 2009)•“Decadal exchange“ (lead Hadley Center1)
1. Smith et al. (2012) submitted to Climate Dynamics
Decadal climate predictions - a candidate for climate services?
YES•time-horizon appropriate for decision making •indication of predictability for certain quantities
RECOMMENDATION •develop a system for decadal climate predictions (e.g. World Summit 2009)•“Decadal exchange“ (lead Hadley Center)
Key Question can predictability be established?MiKlip project1
1. www.fona-miklip.de
Research challenges
Only difference between hindcasts is the initialisation datasetRight panel - clear improvement over the tropics
Initialisation
BAD GOOD
Correlation with HadISST for lead year 2
Graphic from H. Pohlmann, MPI Meteorology
Only difference between hindcasts is the initialisation datasetRight panel - clear improvement over the tropics
Need: Initialisation techniques and state estimates
Initialisation
BAD GOOD
Correlation with HadISST for lead year 2
Graphic from H. Pohlmann, MPI Meteorology
Lack of robust decadal climate variabilty in global models•differences in the representation of processes e.g., AMOC•missing processes
Processes
Lack of robust decadal climate variabilty in global models
Need: increased process understanding
Processes
Increased relevance for usersBut, so far: •little focus on regional modelling + decadal climate prediction
Regionalisation
Graphics from Andreas Will (BTU Cottbus) and DKRZ
Little regional modelling + decadal climate prediction
Need to: – investigate key regions – combine global and regional models
Regionalisation
Graphics from Andreas Will (BTU Cottbus) and DKRZ
How do we judge what information is of use? •Scientific perspective:
– Skill (statistical)
•Societal perspective– Usefulness /applicability for decision making
Evaluation
How do we judge what information is of use? •Scientific perspective:
– Skill (statistical)
•Societal perspective– Usefulness /applicability for decision making
NEED to: •develop tools and methods to evaluate skill of decadal predictions•involve potential users
Evaluation
Ultimate challenge: system for decadal prediction
MiKlip project aim
Exchange of results during project development stages
Project coordination: J. Marotzke, D. Stammer, U. Cubasch, Ch. Kottmeier, U. Ulbrich, P. Becker
A framework for decadal climate predictionMiKlip project
Making skillful (and useful) predictions
„Roadmap“ for making decadal climate predictions part of a climate services portfolio
Overview
Current decadal prediction system“Baseline 0“
Global model: MPI-ESM-LR•Historical run: CMIP5 (all forcings) •Hindcasts: - 1961 – 2011
- initialised yearly- 3 ensemble members (10 for 5th year)
Global model: MPI-ESM-LR•Historical run: CMIP5 (all forcings) •Hindcasts: - 1961 – 2011
- initialised yearly- 3 ensemble members (10 for 5th year)
Skill measure for hindcasts•RMSE compared to
– historical runs– persistence
Current decadal prediction system“Baseline 0“
Initialised experiments compared to historical: skill in North Atlantic, reduced
skill in tropics, low skill over land
Müller et al. (2012) submitted to GRL
GOOD
BAD
Global mean surface T – lead year 2-5 RMSE w.r.t. HadISST & GHCN-CAMS
Prediction of quantities with known skill+ confidence in physical mechanism
Graphic from H. Pohlmann, MPI Meteorology
Prediction of quantities with known skill+ confidence in physical mechanism
• How relevant is this information from a climate services point of view?
Graphic from H. Pohlmann, MPI Meteorology
Boosting skill by reduced time-interval? – seasonal patterns in EuropeRMSE for Sept-Oct-Nov
Müller et al. (2012) submitted to GRL
Boosting skill by reduced time-interval? – seasonal patterns in EuropeRMSE for Sept-Oct-Nov
Müller et al. (2012) submitted to GRL
Boosting skill by reduced time-interval? – seasonal patterns in Europe
RMSE Sept-Oct-Nov in Eastern Europe
Müller et al. (2012) submitted to GRL
HindcastsPersistenceUninitialised
RSME lower for initialised runs, but not as consistent as for annual means
Boosting skill by reduced time-interval? – seasonal patterns in Europe
RMSE Sept-Oct-Nov in Eastern Europe
Müller et al. (2012) submitted to GRL
HindcastsPersistenceUninitialised
• Inter-decadal trend more realistic in regional modelpotential for increasing skill by using regional model contingent on global model skill in SSTs
Boosting skill by regionalisation ? 1961-99 summer rainfall trend over N Africa
Global (ECHAM5) Regional (REMO) Obs. (GPCC)
Graphic: Prof. H. Paeth and A. Paxian, Uni Würzburg
-1500 -200 - 20 20 200 1500 (mm/yr)
Baseline 0 Baseline 1 (new initialisation)
Baseline 0: decadal trend in Atlantic SST not capturedBaseline 1:
Positive correlation for the whole Atlantic basin SSTs necessary for n. Africa might be better capturedHighlights the need for several iterations within the project
Updating the decadal prediction system
With the global model: •robust skill for some regions (e.g. North Atlantic)•indication of increased skill over land when considering seasons With the regional models: •potential for added value, if skill in the global model can be established
Skill summary
With the global model: •robust skill for some regions (e.g. North Atlantic)•indication of increased skill over land when considering seasons With the regional models: •potential for added value, if skill in the global model can be established
Promising results, but a lot of work before being able to offer a „range“ of regions/times/quantities with skill
Need iterations involving all MiKlip modules
Skill summary
A framework for decadal climate predictionMiKlip project
Making skillful (and useful) predictions
„Roadmap“ for making decadal climate predictions part of a climate services portfolio
Overview
Roadmap1. Establish confidence in skill before involving users
Framework for decadal predictionImprove system skill (and understanding) from a scientific perspective This is where MiKlip (and others) are now
Decadal climate predictions as part of a climate services portfolio
Roadmap1. Establish confidence in skill before involving users Once potential for skill has been demonstrated: 2. Involve users in particular regions/with particular quantities of interest
– e.g., useful indices, seasons, quantities
Decadal climate predictions as part of a climate services portfolio
Roadmap1. Establish confidence in skill before involving users 2. Involve users in particular regions/with particular quantities of interest When users have been involved 3. Pin-point processes, regions and evaluation tools necessary for users‘ needs
improvement of skill system from a user/climate services perspective
Decadal climate predictions as part of a climate services portfolio
Roadmap1. Establish confidence in skill before involving users 2. Involve users in particular regions/with particular quantities of interest 3. Pin-point processes, regions and evaluation tools necessary for users‘ needs 4. Provide decadal predictions for climate services
Decadal climate predictions as part of a climate services portfolio
Roadmap1. Establish confidence in skill before involving users 2. Involve users in particular regions/with particular quantities of interest 3. Pin-point processes, regions and evaluation tools necessary for users‘ needs 4. Provide decadal predictions for climate services
Decadal climate predictions as part of a climate services portfolio